In many applications for which administering devices are used, the demands placed on them in terms of water tightness are high. This is of particular importance in situations where drugs are self-administered, as is common practice in the case of treatment for diabetes, for example. In terms of their external dimensions, administering devices have now become so small that they can be carried in virtually every day to day situation, for example during sport, whilst showering and even in water. Under all circumstances, it must be possible to guarantee water tightness under the conditions which can be anticipated during the time leading to the expiry date, and administering devices are designed to be serviceable for several months or even years. Water tightness is problematic because the housings of administering devices are not only required to protect moisture-sensitive components from moisture, but must also fulfill other functions. For example, it must be possible to use a key pad, which is itself sensitive to moisture or is at least connected to moisture-sensitive components. It must also be borne in mind that a visual, acoustic or tactile indicator, for example a vibrating display, also has to be protected from moisture. In the case of a visual indicator or display, the reader must be able to read the functions presented on the display through a transparent see-through region.
As a rule, the housings of administering devices therefore have openings, in which flexible or transparent wall elements are inserted. In order to guarantee water tightness, the wall elements are adhered along the edge of the respective opening to an otherwise watertight shell structure of the housing or are joined by ultrasound welding or some other means. In addition to molding the housing structures, namely the shell structure and the wall elements which have to be inserted, the process of manufacturing the housings requires other joining operations, namely the insertion of the relevant wall elements followed by their connection by means of another joining technique, such as bonding or welding for example. The additional joining process incurs costs and constitutes new sources of faults, which can lead to faults in the seal and in any event, increases the amount of work involved in quality assurance.